A long, long time ago we wrote a short, simple tech article explaining how to play with the mixture screws on an Edelbrock carburetor. Looking back, it wasn't a great article; it was just sort of adequate. That short little piece, however, has brought us bags and bags of e-mail about how to fix carburetors.
We have a confession to make: we don't like carburetors. We are strongly on the fuel injection side, especially electronic sequential injection. Less than 20% of the cars we've owned have had carburetors on them. But you guys keep on writing in anyway, so we use what little we know to try to get you back on the road. Our big hope is that one of you old-timers who loves carburetors will take it upon yourself to help answer these poor souls when our own pathetic scratchings come up wanting.
If you'd like to make a Cave Drawing of your own, please report to the Main Cave.
From Bill Reachme on 22 February 2003:
I have a 600 cfm edelbrock (electric choke) on a 350 chevy. At cold idle
while choked it's racing way to high. How do I turn this cold idle down.
All other operations of carb are fine. It starts great, idles when warm
great and performs as it should. Any help would be appreciated!
There's a little screw on the side of the carb that controls the cold idle speed. It's in the rat's nest of linkage where the throttle cable connects up. It's not too hard to spot. Play with that screw till the idle is where you want it.
From Coyote Boy on 30 January 2003:
Hello I have a 625 carter AFB that will not idle good and it makes a popping
noise on passenger side exhaust only . Compression is 165 on all cylinders
and vaccum is 15.5 . Problem is in the carb because I put a junk holley 600
and it works great idle is good and power is decent i'd rather have the AFB.
Can you help
Have you adjusted the fuel mixture? How old is the carb: does it need to be rebuilt?
From Jerry Holway on 30 January 2003:
Thank you for the tips on adjusting the Edelbrock. I have a problem with
mine I hope you could help me with. I have it on a 1983 Chevy PU 350.
It's been on for a couple of years and has been going great. Recently
the gas peddel has been getting harder to press down. I've tracked it
down to the carb. With the engine off, the gas is easy to push but with
the engine running, either idle or 55 mph, it's hard to push down. It
diffently appears to be in the carb. I would apppreciate any advice.
Thanks for your help.
That's a very odd problem. Maybe it's time for a teardown, or maybe the throttle cable is binding on something.
From Jay Sharp on 12 January 2003:
Do you have photos of how to lower the r.p.m. when the electric choke is
engaged? Mine seems to be way to high! PS the carb is a "perfomer series"
No, I don't, but it's pretty painless. Look on the side of the carb and you'll hopefully see where the trottle cable links to the carb. Around there you'll see a fairly tiny screw that controls the idle speed of the carb. Adjust that to adjust the speed.
From The Bluf on 6 January 2003:
is the 2 screw adjustments the same on an electric choke carb?
Shouldn't matter what kind of choke you have.
From Halle Welch on 29 December 2002:
My carburetor sat for about 6 months without any stabalizer. I have take=
n it apart and cleaned it but do not know how to clean the internal passa=
ges. What can I do?
Dunk it in a bucket of carb cleaner for a while.
From Gilbert Couture on 26 December 2002:
I have a 74 Charger 400 magnum with a thermoquad carburator and i have a
trouble with it,i have trouble to start,if a give gaz it's like if the
engine want to stall,and if i give too much it's like if the engine want
more,all is new,all is okay but just for starting,the four barril run
great,but this is just for starting,i start with the torq of the
engine.I can make burnout but i can not start normaly.Timing is
good,plug,rotor,distributor are good,the engine have 54 000 miles,i'm
from Quebec in Canada,i know one person who rebuilt thermoquad
carburator,he rebuilt mine and it have this trouble,this is the
problem,if you can send me information,manual or something to help me i
will be happy,i bought this charger when i was 15 years old,now,i'm
17,the car never see the snow,original paint,vinyle top,that was my
dream to have this,now i would like to have a car who run great,thank
you,sorry for the language,i speak french. Gilbert Couture
Sounds like your choke is buggered.
From Scott Lundberg on 24 November 2002:
I was looking for some troubleshooting info on a 1406 edelbrock and ran
across your page. I have some feedback on that page and another question I
hope you can help me out with.
The feedback is this: You might want to clarify that the two screws on the
front of the carb are idle A/F jets, NOT main A/F jets.
The question is this: I had a couple backfires when the cold weather hit
and ever since then I have had a misfiring and bogging/surging at just
off-idle cruising speed. It does not matter what the RPM is. I noticed
that it had totally fouled the spark plugs and I changed them. In my
investigations, I noticed that at about 1400 RPM with car out of gear, that
the passenger side main gas discharge is intermittentantly spitting large
amouts of gas, while the driver's side does not. It actually makes a
spitting sound as it happens. This does not happen at WOT (although since
both sides are spitting so much gas, I probably wouldn't be able to tell)
nor at idle. I was thinking float at first, but since it doesn't happen at
idle, I have ruled that out...
The idle vaccuum is about 10 inches and when I first start noticing the
spitting, is at 12-13 inches. At 15 inches, it goes away. I have checked
to make sure that the main rod on the passenger side is not lifting up off
the jet seat. Can you tell me if a plugged well vent could cause such a
problem? Any other ideas that I haven't mentioned here?
relevant specs on car:
#1406 Edelbrock Carb
Edelbrock Performer Manifold
You won't like this suggestion, but I'd probably start taking the bugger apart till I found whatever piece is not doing its job.
From Brenda Hamby on 6 November 2002:
I am having difficultiing with my 69 Chevy van,350 engine,Edelbrock
carb.Manual choke.It floods when engine is dead.I understand how to set mixture
needles also have set floats,had a carb kit installed.Please HELP!Thanks!
More than likely your floats are dead. No adjusting in the world will compensate for 'em.
From Louis Crosby on 17 October 2002:
GOOD EVENING sir, my partner has an 79 chev that stall when he put the car in
gear. the car runs smoothly while idled, but as soon as he puts it in gear it
stops. he changed the spark plug wires, distributors, rotor, fuel pump and
even the filter in the gas line.
with the line detached from the carburetor you can see the gas being pumped
from the fuel pump. after all that is said and was done could you tell me
what could be the problem for the car not running. THANKS FOR ANY GOOD
Someone send this guy an e-mail telling him how to fix his car. I don't know for sure what it is.
From David Neal on 28 September 2002:
my wife is driving me nuts, her #@*+++ festiva willnot start in the morning or
if it is below 65 degrees. it starts fine in theafternoon. so far i have
replaced the rotor, dist. cap, fuel filter. it has spark and the fuel pump is
pumping. in another life, if you had fuel and spark then your engine would
start. can you help???
Your engine is getting choked up. Check the carb choke, or if your car is fuel injected, its equivalent.
From Parish Stout on 16 September 2002:
i need to know the proper place to hook the vaccum advance line on a chevy hei
distributor, my buddy said it was on the intake and i said it was to a timed
vaccum port on the caurberator whos right? its on a 72 chevy pickup with a 327
Try the carby, see what happens.
From Vince Horn on 11 September 2002:
I have '73 Ford Gran Torino with a 351W and I need to rebuid the carb on it.
How can I tell exactly which carb is on it, and is there an online manual I
could download that would assist in the process.
Also, would it be worth changing the jets on it to gain a little more power, and
if so, how much can you change them without sacrificing too much gas mileage?
You can identify the carburetor by removing it and having a look for stampings. The manufacturer, serial number, and model number are all likely to appear on it somewhere. You can be pretty sure there is no online manual unless an enthusiast posted one. Hard to say about changing the jets without knowing what it's got and how it's running.
From Nate Nickels on 15 August 2002:
On my car the engine is not running right
i have rodchester quadra jet carb and it chokes and i cant get over 50 mph
is this the choke broken ?
Hi Nate. Definitely, if the carb is still choking the engine at 50 mph, something's broken.
From Danny Hall on 14 August 2002:
Could you tell me the CFM for this carb? Thermoquad #6452s. I can't seem to find
out, other than it was on a manual trans. 360 in 1974. Thanks
Sorry Dan, I have no idea. Try asking Carter.
From a hardware guy on 24 June 2002:
I have a one of a kind 1982 GMC Jimmy 2-wheel drive.It has a 454 engine with
a Edelbrock high rise intake,a 800 Edelbrock carb,Edelbrock headers and Flow
Master exhaust.I'm running 550 h.p but at high speeds it has a miss like the
carb is sputtering.How do you adjust an 800 Edelbrock.
You start by buying a carb tuning manual from Edelbrock.
From Roxana Mitsuko on 14 June 2002:
I would appreciate any info you can give me on float adjustments on the 1405 carb. I
rebuilt the carburetor, changing gaskets, cleaning out the gump, etc.
I have been having problems with gasoline spewing out from the plunger and as I shut
off the engine gasoline spews out everywhere. I was told that one can adjust the
floats so that less gas is fed to the ports and that problem should resolve.
I don't see what there is to adjust, unless of course I am missing a crucial part
inside the carburetor that I am not aware of.. Is it possible to see a 1405
disassembled so that I can check against the carb I have? I got this one used so I am
not sure about missing part since I don't seem to find anything to adjust the floats
with. I will be grateful if you can help me. Thank you for your time. Roxana
You definitely need to contact Edelbrock and buy a manual for that carb. Your life will be much better that way.
From Chadrick Renowden on 9 June 2002:
How do I lean out my carb ,I have a edelbrock 1406 1402 are the numbers on the bottom
of the carb. I have it on a 1978 ford bronco 351m. I have to lean it out for emission
You do it by buying a manual from Edelbrock and following the directions in it. (But in the meantime, you might have some luck by turning on those two huge screws on the front of the bloody thing.)
From Billy Jalufka on 8 May 2002:
EDELBROCK 600 CFM
I HAVE THIS CARB ON A BRAND NEW EDELBROCK INTAKE MANIFOLD ON A BRAND NEW
CRATE CHEVY 350. IT RUNS GREAT IF YOU DRIVE UNDER 40 OR 50 MILES PER HOUR.
IF YOU TRY TO GET OVER THAT SPEED OR STOMP IT, IT WILL BOG DOWN AND WON'T DO
PLEASE TELL ME WHAT I CAN DO OR TRY?
Start by prying the Caps Lock key off your keyboard and feeding it to the dog. Then, it sounds to me like the engine is getting flooded when the secondaries kick in. Time for some tuning. If you don't have an Edelbrock manual yet, this is your cue to get one.
From Mark Bologna on 31 March 2002:
i have the adjustments 4 a 318 charger can u help me with a pontiac lemans 400 engine
same carb 600cfmedlebrock the car has a mild cam dual exaust holly intake the engine
has some workbut the carb air and fuel is way off can u send me or help me get it in
Your 600 cfm Edelbrock carburetor was manufactured by Edelbrock Corp. Edelbrock Corp. is still in business and still builds carburetors. They even still build 600 cfm carburetors. Probably they have attached one or two of them to a Pontiac engine at some time. They have a website with technical information on it. That would be a much better place to start than with some stranger who makes fun of the people who write to him for help, especially when you've written before and I made fun of you just as much last time!
From Mark Bologna on 20 March 2002:
hi my name is mark i have a pontiac lemans just dropped in a pontiac 400 engine .
witch is worked dual exaust a cam the whole nine yards holly intake with a edlebrock
carb i think its ether a 650 or 700 edlebrock 4 barrel carb with the air mix screw on
the left and gas wix screw on right whats the correct mixture can you help me get
this mixture correct theres no choke 1973 isthe year of car if that matters
Go to Edelbrock's website where you'll find a handy dandy tuning guide written by folks who use these things a lot more than I do.
From Robin O'Carroll on 13 March 2002:
I purchased and installed a #1400 Edelbrock carb with elec choke. Problem I cannot
get rid of is difficulty starting in the mornings. Have contacted Edelbrock techs on
3 occasions for help.
All electrical working fine
All rod and top plate measurements are correct
Elec choke works normally
Float levels checked OK
Fuel pressure between 4.5 and 5.0 at idle
Have to pump the fuel several times in the mornings before the car will fireup. Once
running there is no problem restarting after turning off, unless the car sits for
several hours when the problem starts all over again.
Even tried every combination of jet and needle combination based on their chart.
Every change from standard gives me varying degrees of hesitancy and pulling whether
in the power mode or the cruise mode. Do these things really work?
Any direction on cold start would be greatly appreciated. So far disappointed with
product. Never had this type of problem with original Quarajet.
It's normal for a carbureted engine to need a couple pumps of the gas pedal when cold. If that's the only problem you're experiencing, then everything is probably working fine. Return the poor thing to its original configuration.
From Tony Soares on 11 March 2002:
I'm going to install an Edelbrock carb that I have on a project truck I'm working
on, it's got a mild 350 Chevy S.B. in it and the carb is a 1400 ( the smog legal
carb). I had the carb on another car that had to pass smog. I afraid that the
carb will be too lean when I install it on the 350. Can you recommend any jetting
changes or tell me where to find such info any help would be great. I've never
seen any books on Edelbrock carbs like the ones on Holleys.
Thanks Tony S.
Eh, the 1400 is designed to drop on a smallblock Chevy out of the box, so you're probably fine. But, if you really want to play with it, Edelbrock offers a tuning guide on their website.
From Vincent the Dumb Kid on 16 August 2001:
I have a 1967 Mustang coupe with a 289. My dad and I just replaced the tiny
stock 2 barrel carb with an Edelbrock 1406, and the car runs great, except
gas mileage SUCKS. I am getting about 8-10 miles per gallon on the car, and
once I noticed such a huge dent in my gas gauge, I cut back on flooring it,
and drive it even slower than I did with a two barrel, but gas mileage
remains about the same. It is still stock calibration, and I believe it is
running a little rich. Im not sure if it makes THAT much difference running
rich, but I used to get about 15-18 miles per gallon with the two barrel. Im
also moving from sea level to 5,000 foot altitudes in about two weeks, so
will that lean the mixture and help mileage climb back up? I love the
performance, but being a daily driver, it makes it difficult to appreciate,
especially while in college. Any help is appreciated.
Owner of 1967 Mustang (Eleanor)
Actually, Eleanor was a 1973 model -- even if the car in the remake IS cooler. But to your
question: I dunno that you'll ever get your old fuel economy back, but it's almost certainly
running rich. 600 cfm for a little ol' 289 with few performance mods is probably way too much.
Lean that guy out a bit (or put on enough performance parts to justify 600 cfm) and see what
happens. 'Course, the best thing would be to tune it at a dragstrip or on a dyno. Got one?
From Robert Gus on 28 December 2000:
Having not paid attention to my father when I was younger I am starting way
behind the power curve on working on cars. So don't laugh at me to hard when
you read my questions, you might even want to put the tips up at your site,
which btw did answer a couple of questions, thanks
1. I have a 67 Mustang FB, 289ci, 4 speed. I have recently had the motor
overhauled and up graded a few items on it. My question is I want to install
the Edelbrock F28 2x4 intake I found in my dads garage, I was thinking of
going with a couple of Edelbrock 1405's or 1406's with the chokes removed. I
don't do any cold weather driving so I didn't think not having a choke would
matter. I was wonder what I should jet the pair of carbs at, and which
metering rods should I use.
2. I was reading some stuff the other day and it recommended that 2x4
intakes should use a electric fuel pump and an adjustable regulator. What do
please let me know if you post the tips at your site.
thanks for all of your help
Hi Bob! May be just me but I think you are waaaaay-overcarbureting that little 289. A single
4bbl will probably work much better. As far as specifics, if you do go with the dual quad setup,
I'll have to recommend that you talk with Edelbrock directly. I've found them helpful in the past
and they should do a better job dialing in your combo (since you're using their stuff) than I could.
My car needs a little choke on first startup even in the dead of summer, so you should probably
retain the choke mechanism -- nothing to be gained by removing it, really. You might wanta
think about keeping the electric chokes though. Mine's a manual choke and the novelty wore off
several years ago. Next time I go over this engine I'm switching. As far as fuel delivery goes,
with the 2x4s you will probably need something. If you stick with a single 4bbl, you probably can
run on the stock system.
From Steve Fisher on 18 December 2000:
Don't know if you can help me but I will ask anyway. I just put this [600 cfm]
carb. on my 82 Chevy, 396/402 engine. I can't seem to get the carb. adjusted
properly. I read what ya'll stated about the 5 1/2 turns, at this point is
it suppose to be correctly adjusted or is this where you start from? Right
after that you stated that yours was properly adjusted at 3 1/2 turns, so
does that mean 3 1/2 turns from start "Where the screws are all the way in"
or from the 5 half turns point. If it is from the 5 half turns point, is
this turning it in or out 3 1/2 turns. I am sorry that I sound stupid, but I
am having a rough time with this damn carb. When I punch it to the floor it
start popping back and I can't get it to stop, right now I have it so lean
it hardly idles, but that is what the carb. manual said, was to lean it down
to get it running better. PLEASE HELP.....
Slam N Kustoms
Hi Steve, I can see how you found that page a little confusing. It was one of the first ones I
put online, so it's not really up to the quality I hold current material to. Anyway, to help you out. I
adjusted mine with the car idling so I could listen to it. I took one screw waaaaay out so that the
engine would stay running (barely) after I put the other screw all the way in. Then, I took the
screw that I had just tightened and backed it out 5 half-turns (a half-turn being 180 degrees, or in
other words 2.5 full circles). Then I took the other screw, the one that was way out, and threaded
it all the way in. Then I backed it out 5 half-turns, so now the two screws were balanced. Then, I
adjusted the screws together (what I did to one, I did to the other) until the car seemed to run
good. Since I knew where the screws were located compared to being all the way in, I kept track
of the screws' positions based on that. Thus if I started at 5 half-turns and went in 2 half-turns (1
full 360 degrees) then I was at 3 half-turns from all-in. Ultimately my car seemed to work best at
4.5 half-turns from all-in. One thing you might think about is maybe your carb is too small for a
From Robert W. Marshall on 1 August 2000:
I have an Edelbrock electric choke kit 1478 I want to install on my
Edelbrock Manual choke carburetor 1405. I do not have the instructions.
Can you help?
Nope. Mine is still a manual choke. I'll bet if you contact Edelbrock, they'll send you instructions.